UN 3400 — Organometallic substance, solid, self-heating
Placard: Spontaneously Combustible. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3400 is Organometallic substance, solid, self-heating, a broad organometallic entry assigned to ERG Guide 138. The main concern is self-heating and possible moisture reactivity; exact compound/SDS verification is critical.
Hazard overview: SELF-HEATING organometallic solid; may heat and ignite under air exposure, moisture or poor heat dissipation. Some products may also react with water to release flammable gases and heat. Large piles, damaged packaging or contamination can accelerate self-heating.
Response guidance: For UN 3400, isolate the area, keep all water/moisture away and use SCBA from a protected position. Use compatible dry media only and watch for re-ignition under ERG 138.
Firefighter training notes: Training for UN 3400 should emphasize pyrophoric/water-reactive behavior, dry-media tactics, re-ignition checks, moisture exclusion, SCBA use and runoff/debris control. Use ERG 138, SDS and local SOP.
Regulatory context: Organometallic substance, solid, self-heating is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, concentration, formulation and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Organometallic substance, solid, self-heating should be stored dry in compatible sealed containers under inert gas or approved protective liquid where required, away from water, moisture, air, heat, ignition sources and oxidizers.
UN 3400 Quick Details
Common Hazards of UN 3400
- SELF-HEATING organometallic solid; may heat and ignite under air exposure, moisture or poor heat dissipation.
- Some products may also react with water to release flammable gases and heat.
- Large piles, damaged packaging or contamination can accelerate self-heating.
- Water, foam, CO2 or halogenated agents may be incompatible depending on exact compound.
- May re-ignite after apparent extinguishment.
- Fire may produce toxic metal oxide fumes and irritating organic smoke.
- Exact metal, ligand, particle size, solvent and package condition must be verified from SDS.
Chemical Identity & Physical Properties
Solid material, color varies by specific compound. May be powder, granules, or crystalline. Often pyrophoric with potential for spontaneous ignition in air or upon contact with moisture.
| Also known as | Organometallic compound solidSelf-heating organometallic materialPyrophoric organometallic solidMetal-organic compound self-heating |
| Appearance | Solid material, color varies by specific compound. May be powder, granules, or crystalline. Often pyrophoric with potential for spontaneous ignition in air or upon contact with moisture. |
| Flash Point | Not applicable (pyrophoric solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts vigorously to violently with water producing flammable gases. May ignite spontaneously on contact with water or moist air. Do not use water for firefighting. |
Fireground Response Guidance — UN 3400
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA with fire/chemical protection and distance from reactive material. Level A or B may be needed for unknown compound, vapor, splash or residue contact.
Isolation & Evacuation
First Actions for a UN 3400 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Exclude water, moisture, foam and incompatible extinguishing media.
- Avoid disturbing residue because pyrophoric or water-reactive material may re-ignite.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, dust, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 138, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3400 — Organometallic substance, solid, self-heUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.